1. Technical Field of the Invention
The present invention relates to a device for adding harmonics to a sound signal, and more particularly, to a harmonic adding device for easily setting or changing the quantity of added harmonics, the ratio of odd-numbered harmonics to even-numbered harmonics, etc.
2. Description of the Related Art
A harmonic adding device adds harmonics to a sound signal by inputting the sound signal to a circuit having a non-linear input/output function (input/output characteristics) to distort the waveform of the sound signal, thereby controlling sound quality and providing sound effects. Conventional harmonic adding devices are disclosed in patent references 1, 2 and 3. The harmonic adding device disclosed in patent reference 1 sets a non-linear input/output function using a non-linear characteristic (S-characteristics) of a transistor. The harmonic adding device disclosed in patent reference 2 sets a non-linear input/output function using an external circuit connected to an operational amplifier. The harmonic adding device disclosed in patent reference 3 sets a non-linear input/output function according to a non-linear characteristic stored in a gain table.
[Patent Reference 1] Japanese Patent No. 3605363
[Patent Reference 2] Japanese Patent Application Publication No. 2006-267790
[Patent Reference 3] Japanese Patent Application Publication No. 2007-178675
According to conventional harmonic adding devices, the quantity of added harmonics, the ratio of odd-numbered harmonics to even-numbered harmonics, etc. cannot be easily set or changed.